Palace of Fine and Decorative Arts, Treasure Island, Historic aircraft hangar on Treasure Island, San Francisco, United States.

The Palace is a large concrete building with distinctive corner towers and modern architectural style that was originally built as an aircraft hangar in the 1930s. Its interior was subdivided using temporary walls to create separate exhibition galleries.

Building 3 was completed in July 1938 as one of two identical reinforced-concrete hangars for Pan American Airways' trans-Pacific Clipper flying boats, designed by George W. Kelham and William Peyton Day. For the 1939–40 Golden Gate International Exposition it gained a 48,600-square-foot stucco-clad addition with four corner towers and housed a $20 million art collection. The U.S. Navy then used it as an equipment repair center until the station closed in 1997; it joined the National Register of Historic Places on February 26, 2008.

The 1939-40 fair filled the hangar with a $20 million art collection shown in small galleries behind curving temporary plaster walls designed by Dorothy Wright Liebes and Shepard Vogelsang. For the 1940 season Diego Rivera painted the Pan Am Unity fresco here. The fair closed on September 29, 1940, still in debt.

The site is located on Treasure Island and can be reached by public transportation that connects to the mainland. Visitors should know that the grounds are spacious and weather on the island can be quite windy.

The 48,600-square-foot exhibition addition wraps three sides of the hangar, and four concrete corner towers rise almost 68 feet. From the other elevations the taller hangar section looms over the additions, so the building's aircraft-hangar origin stays visible.